The ground beneath Kilauea’s summit is swelling with fresh magma, and the next eruption could break through at any moment. The U.S. Geological Survey’s Hawaiian Volcano Observatory expects episode 48 of the ongoing fountaining sequence to erupt from Halemaʻumaʻu crater between Monday, May 25, and Tuesday, May 26, 2026, according to the observatory’s latest Kilauea status update. Summit reinflation has been building steadily since episode 47 ended on May 15, and tiltmeters are tracking the same pattern that preceded every recent outburst: a slow, measurable rise toward the threshold where lava forces its way to the surface.
For the roughly two million people who visit Hawaii Volcanoes National Park each year and for residents living downwind of the crater, the forecast carries real weight. These episodes can ignite with little warning, send lava fountains tens of meters into the air, and end within hours, making the window between “likely soon” and “happening now” uncomfortably narrow.
What episodes 46 and 47 actually looked like
To understand what may be coming, it helps to know what the last two episodes delivered. Episode 46 and episode 47 both followed the same script that has defined this eruption sequence: a period of steady summit inflation, minor spattering as a precursor, and then a rapid onset of full lava fountaining from vents on the floor of Halemaʻumaʻu crater. During these events, fountains reached heights of roughly 30 to 50 meters, according to HVO observations, coating the crater floor with fresh lava and sending plumes of volcanic gas and fine tephra downwind. Each episode lasted on the order of hours, not days, with episode 47 running from May 14 to May 15 before fountaining shut off as the magma reservoir deflated.
The Hawaiian Volcano Observatory’s formal hazard notice for episode 47 documented the fountaining duration, effusion rates, estimated lava volume, crater-floor coverage, and the sharp deflationary tilt that signals magma draining from the reservoir into the eruption. Once the pressure dropped, fountaining stopped, the crater floor settled, and the cycle reset.
That reset is now well underway. Tiltmeters at the summit have recorded steady inflation since May 15, meaning magma is refilling the shallow reservoir beneath Halemaʻumaʻu. HVO’s forecasting method, described in detail in a Volcano Watch explainer published by the observatory, compares the current rate of inflation against the tilt thresholds that preceded earlier episodes. When the numbers converge, the observatory issues a forecast window. That window is now open.
What scientists can and cannot predict
The two-day window is the best estimate available, but it is not a countdown clock. HVO has been transparent about the limits: the forecast is a probability-weighted expectation, not a guarantee. If inflation stalls or accelerates unexpectedly, the window could shift. The observatory has not published the exact real-time tilt and GPS deformation values for this reinflation phase, which means outside analysts cannot independently verify how close the system is to triggering.
Specific details that will only become clear once the eruption starts include the height of lava fountains, the volume of erupted material, and the geographic reach of volcanic gas and fine ash. Earlier episodes produced ashfall advisories and vog warnings across parts of the Big Island, and similar hazards are expected this time. But the intensity and direction of those hazards depend on wind conditions and fountaining vigor at the moment of eruption.
One question volcanologists are watching closely is whether the intervals between episodes are changing. A shortening gap could signal that the magma supply rate is increasing, while a lengthening one might suggest the system is winding down. HVO has not released a public comparison of tilt data across the last several episodes, so the pattern remains an open area of analysis rather than a settled conclusion.
Aviation alerts and park preparations
The aviation color code for Kilauea remains at ORANGE, and the volcano alert level is at WATCH, according to the observatory’s aviation notice archive. That designation means an eruption with significant ash or gas emissions is expected or already underway, and airlines operating near the Big Island adjust flight paths accordingly.
Hawaii Volcanoes National Park has established protocols for translating HVO forecast windows into visitor safety actions. Trail closures, tephra-fall warnings, and volcanic gas advisories can go into effect rapidly once fountaining begins. The park advises visitors to check USGS webcams and daily updates before heading out, because eruptions are episodic and may only last a few hours before pausing again. Crater overlooks, summit trails, and nearby parking areas are all subject to closure on short notice.
“We want people to experience the volcano, but safely,” a Hawaii Volcanoes National Park spokesperson told visitors in a recent advisory, urging them to treat HVO forecasts as the primary planning tool and to be prepared for rapid changes in access.
What residents and visitors should do now
For anyone on the Big Island, the most practical step is to treat the forecast window as a period of heightened readiness. Visitors planning trips to the park should build flexibility into their schedules and check the latest HVO update and park advisories the morning of any planned visit. Conditions can change faster than social media posts or travel blogs can keep up with.
Residents downwind of the summit, particularly in communities along the Kaʻu coast and in parts of Kona where vog tends to accumulate, should prepare for short but potentially intense episodes of poor air quality. That means having N95 masks or respirators on hand for sensitive family members, planning indoor activities for children and older adults if conditions deteriorate, and reviewing local guidance on limiting outdoor work during peak emissions. Because episodes typically last hours rather than days, these precautions are brief but worth taking seriously.
Emergency managers and community organizations can use the current pause to reinforce a basic distinction that often gets lost in headlines: episodic summit fountaining is a very different hazard from the long-lived lava flows that threatened neighborhoods during Kilauea’s 2018 lower East Rift Zone eruption. Summit episodes are visually dramatic and produce air-quality concerns, but they do not send rivers of lava toward populated areas. Clear communication about that difference helps prevent unnecessary alarm if episode 48 arrives with a burst of fire and then goes quiet again within a day.
How a century of monitoring sharpened the forecast
Kilauea is one of the most densely instrumented volcanoes on Earth, and the roots of that monitoring run deep. The Hawaiian Volcano Observatory was founded in 1912, and scientists have been recording eruptions, measuring ground deformation, and refining eruption models at the summit ever since. What has changed in recent decades is not the existence of monitoring but its density and speed: HVO now operates networks of tiltmeters, GPS stations, seismometers, gas sensors, and webcams that feed data into forecast models in near-real time. The episodic pattern of the current eruption sequence has given scientists a repeating natural experiment, with each cycle of inflation and fountaining adding another data point to the model.
“Each episode teaches us something new about the plumbing beneath the summit,” HVO scientist-in-charge Ken Hon noted in a recent Volcano Watch column, describing how the repeating inflation-deflation cycles allow the observatory to refine its forecast thresholds with every eruption.
That does not eliminate uncertainty. The exact start time, the vigor of fountaining, and the downwind gas concentrations will only be known after episode 48 unfolds. But the combination of an established pattern, clear geophysical precursors, and transparent public communication from HVO gives everyone near the volcano a meaningful head start. In a place where eruptions can shift air quality and close roads within minutes, that head start is the difference between preparation and scrambling.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
